In air-conditioning apparatus and refrigerators, there is known a power conversion apparatus configured to drive, by an inverter, a motor to be used for a compressor, a fan, or the like. Further, a smoothing capacitor is connected to an input stage of the inverter, to thereby stabilize a voltage to be output to the inverter. A commercial alternating current is converted into a direct current by a rectifier, and then the current is smoothed by the smoothing capacitor. After that, the current is converted into AC power with an arbitrary voltage and frequency by the inverter, and then the power is supplied to a load such as a motor.
This smoothing capacitor is charged when the power is turned on, and an inrush current that is several times as large as that in the normal state flows from an AC power supply. Various methods are proposed as a method of suppressing such an inrush current (for example, see Patent Literatures 1 to 3). In Patent Literature 1, there is proposed a configuration in which an inrush current preventing circuit including an inrush preventing resistor and a relay is connected in series to the smoothing capacitor, to thereby prevent charging or discharging of the inrush current into or from the smoothing capacitor. In Patent Literature 2, there is proposed a configuration in which a plurality of sets of combination of a relay and a reactor connected in series are connected in parallel to each other, and an inrush current preventing circuit including a relay circuit and a resistor is also formed. In Patent Literature 3, there is proposed a configuration in which a relay is connected in series to a smoothing capacitor through which a small amount of current flows so as to downsize the relay, and a period is provided in which no ripple current is caused to flow through the smoothing capacitor.